After more than a dozen suspicious fires burned through the downtown Orlando area and historic Sanford area in the past two months, authorities are trying to determine whether a serial arsonist is at work in the Central Florida region.

It will likely be several weeks before officials know whether all the fires were related and whether they were accidentally or intentionally set.

Behind the scenes, state and local forensic investigators who specialize in arson detection are studying scorched debris. Meanwhile, detectives are questioning potential witnesses and trying to identify possible suspects and motives.

The first fire was reported at an empty home off Hillcrest Street in Orlando on May 10. Since then six others have been reported in Orlando, with the latest at an empty home near East Washington Street and North Mills Avenue in Thornton Park on July 2.

The next morning, Sanford's historic Little Red School House, one of Seminole County's first public schools, joined six buildings set ablaze within four days.

And in the same time frame, even more fires were reported in the St. Augustine area, according to Lt. Paul Paterson with the Bureau of Fire and Arson Investigation in the Division of State Fire Marshal. Media outlets in the St. Augustine reported four suspicious fires were sparked June 23.

Local and state fire officials along with staffers at University of Central Florida's National Center for Forensic Science, which houses a database of more than 600 liquids known to feed fires, gave insight into the investigative process.

Process of elimination

When a fire breaks out, local authorities are first on scene. They get the first crack at the investigation. Obvious accidental fires can be wrapped up within days by those local fire departments.

But when a blaze is considered suspicious, the State Fire Marshal's Office usually takes over.

"The firefighters put the fire out, and we investigate it," Paterson said. "We do an overall examination of the scene. ... Before we can call it arson, we have to be able to prove that all other possible causes were eliminated."

That process can take several days to several weeks, according to UCF research and program coordinator Mary Williams.

"When an investigator goes to a scene, they are going to try and determine where a fire started," Williams said. "From that location, they are going to collect the debris. ... The idea is to see if an ignitable liquid was used to start the fire."

Students and faculty in the center don't assist with criminal investigations — evidence can only be handled by fire officials so it can eventually be used in court if charges are filed. But they conduct experiments to determine how different accelerants react to flames.

Williams said the charred debris is stored in buckets similar to paint cans and sent to the State Fire Marshal's lab in North Florida. Forensic investigators later put test strips inside the buckets and reheat the evidence in ovenlike devices.

The heating process helps to collect remaining samples of any accelerants that may have been used to burn the debris inside the bucket.

Detectives also take photos of the scenes and study burn patterns, which can tell the story of the origin — usually the area with the worst damage — and path of the fire after the flames are doused.

Each step of the process can take several hours or days. It's then up to detectives to use a combination of forensic analysis and physical evidence to determine arson.

New leads

The Orlando Fire Department has already determined that no flammable liquids were used in its recent suspicious fires. Instead, tree limbs and other discarded materials, such as the lids of plastic bins, were used to kindle slow-burning flames.

So far, evidence suggests that the possible arsonist might be homeless, said Chief Dave Haley with OFD's Arson and Bomb Squad, citing the lack of a flammable fluid such as gasoline and the use of outdoor material.

A homeless person likely wouldn't have the means to transport hazardous materials such as large quantities of gasoline. The flammable materials used in the Orlando fires were usually shoved into crawl spaces behind the old homes, then set ablaze, Haley said.

Although it's too soon to say whether one suspect is responsible for all the fires, investigators have found several similarities between the Orlando fires and those in Sanford and St. Augustine.

Older, vacant homes and buildings are being targeted, but no one has been injured in any of the fires.

The blazes usually broke out between midnight and dawn and were started behind the homes, out of view of potential witnesses, officials said.

Investigators are still trying to identify other similarities that may point to a motive and then eventually a suspect.

A task force of investigators from Orlando, Sanford, St. Augustine and the State Fire Marshal's Office has been created to find any links between the cases.

"People think [fire] is going to destroy all the evidence," Paterson said. "Very seldom does the fire destroy all the evidence. That's the biggest misconception. ... We're working the cases. We just sift, and we can always find something."